Mendix uses traditional RDS database which is not scalable. Japanese developers are very interested in scalable one but not traditional architecture.
Thank you for the comments. But, AWS S3 is just a file system. AWS connectors like Amazon RDS may be easily integrated with Mendix but it is still RDS.
NoSQL means Amazon DynamoDB which does not require scalability management. MongoDB requires a difficult scalability.
Assuming DynamoDb with Mendix, we still need to manage data only for NoSQL. That's the part demanded now.
Check the App store for connectors: The "Database Connector" supports many NoSQL varieties, and there is a AWS S3 connector as well.